Helicopter rotor blade vibrations, due to unbalanced mass, for example, are unavoidable source of noise, reduced performance, and increased failures. The problem of rotor vibration control is addressed in this paper. The results of a feasibility study on the effectiveness and adaptability of reducing vibration and noise of rotating components by disturbing their circumferential symmetry (i.e., irregular blade spacing, geometry, material, and boundary conditions) are presented. The mathematical model and method of analysis are based on an optimum combination of the component-mode syntheses and receptance approaches. The effect of the elastic energy localization (EEL) phenomenon on vibration/noise response of structures carrying rotating components is investigated and incorporated in a novel computer-aided structural design approach. The developed computer model is used to identify all the effective parameters that can reduce vibrations and noise of non-axisymmetric rotating blades. Preliminary results have shown that circumferentially unsymmetrical blade-spacing, for example, has the potential of significantly reducing the propeller noise.
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